In the past, as an object to be authenticated for the biometrics authentication, a blood vessel is used. In general, in an authentication apparatus, a finger is placed at a predetermined position, and an image of a blood vessel in the static finger is picked up. Then, the authentication apparatus registers an image of the blood vessel which is obtained as the result of the image picked up in a memory etc. as information to identify a biological body having the blood vessel, or compares the image with an image of the blood vessel which has been registered so as to determine whether or not a person of the blood vessel is an identical registrant (for example, refer to Jpn. Pat. Appln. Laid-Open Publication No. 2003-30632).
In this kind of authentication apparatus, at the time of the authentication, in case a finger is placed at a predetermined position with the state different from that at the time of registration even by a slight amount, as shown in FIG. 9, the curvature factor is changed even if the finger is the identical finger since the image pickup direction is different. Accordingly, there is raised a problem that the person is determined as a third party even if the person is an identical registrant, which consequently lowers the authentication accuracy.